Kensuke Sasaki was born on August 4th, 1966 in Fukuoka City, Fukuoka. Kensuke was very good at sports and weight lifting and even though he had a smaller stature he proved he was just as good as anyone. After he graduated school he went to train to be a professional wrestler. He was immediately picked by Riki Choshu and on February 26th, 1986 Sasaki debuted against Shinji Sasazaki in Choshu's Japan Pro Wrestling that was a branch of All Japan Pro Wrestling. Choshu's promotion would not last long and on June of 1987 Sasaki followed him to New Japan Pro Wrestling and was placed into the young lions training system. After training, Sasaki left Japan in early 1989 to join Canada's Stampede Wrestling, a promotion run by the late Stu Hart. He found success in the tag division when him and his partner Sumo Hara won the Stampede International Tag Team Titles on August of 1989. They would lose the titles a month later to The Black Harts. Sasaki came back to New Japan and on November 1st, 1990, against Keiji Mutoh and Masa Chono, he won the IWGP Tag Championship with partner Hiroshi Hase. They would lose the titles over a month later to Super Strong Machine and Hiro Saito, but on March 6th, 1991 they won the titles back from them. At the end of March, Sasaki and Hase lost the titles against Rick and Scott Steiner in what was considered the match of the year of 1991. In 1992 Sasaki dawned a new look with face paint and became the one called the Power Warrior. He then teamed with the Legion of Doom, Hawk and Animal Warrior, and they called themselves the Hell Raisers. Almost a month later after running through everything and everyone in their path, both in New Japan and America's WCW, they defeated Scott Norton and Tony Halme to win the IWGP Tag Championship. They would continue the domination for almost eight months before they lost the titles to Scott Norton and his partner Hercules Hernandez on August 5th, 1993. It would not be any time at all before they would get a rematch and on January 4th, 1994 they won the titles back. They held the titles for almost a year and on November 25th, 1994 they would lose the titles to Sasaki's old partner Hase and his partner Keiji Mutoh. After the loss he would stop wrestling as Power Warrior, and he would go back to wrestling as his actual name.

Sasaki would try to rise in the ranks of the single competitors and on November 13th, 1995 he would win his first singles title when during an inter-promotional event between New Japan and WCW he defeated Sting for the United States Heavyweight Championship. The run would be short lived when a month later he was defeated by the One Man Gang. He would go on in 1996 to win a Japan/U.S. All Star Tournament when he defeated Shiro Koshinaka. The next year would start out good for Sasaki when in April he, along with his long time mentor Riki Choshu, won the IWGP Tag Championship from Tatsumi Fujinami and Kengo Kimura. The reign would be short lived when they would lose the titles to Manabu Nakanishi and Satoshi Kojima on May 3rd. It was soon after that Sasaki was announced to be in the G1 Climax Tournament. In August he would make it all the way to the finals to face Hiroyoshi Tenzan in a New Japan versus NWO face-off. He defeated Tenzan with his Northern Lights Bomb, and he finally proved himself as a top singles contender in the sport. Sasaki soon after won the IWGP Tag Team Championship for the sixth time, with Kazuo Yamazaki against Satoshi Kojima and Manabu Nakanishi after winning a special G-1 tag tournament. With the big win at the G-1 tournament Sasaki also earned a title shot against Shinya Hashimoto at the end of that month. That day finally came on August 31st, 1997, and what Sasaki had strived for was imminent. He would end Hashimoto's long reign as the IWGP Champion, winning the IWGP Heavyweight Championship. He would soon after go on to defeat Chono in October, and he would wrestle as Power Warrior against Great Muta in January 1998's Tokyo Dome Show. He held the championship until March 4th, 1998 when he lost to Tatsumi Fujinami. Sasaki's next title win would again be for IWGP Tag Team Titles, on March 22nd, 1999, when he teamed with Shiro Koshinaka to take on Hiroyoshi Tenzan and Satoshi Kojima. They held the titles for over three months.

On January 4th, 2000 Sasaki, even though having a high fever, managed to defeat "Mr. Puroresu" Genichiro Tenryu to win his second IWGP Heavyweight Title. In August 2000 Sasaki won the G1 Climax by defeating Manabu Nakanishi in the finals of the tournament. Sasaki would suffer an injury and on October 9th, 2000 he vacated the title. Almost immediately he would come back and on January 4th, 2001 he defeated Toshiaki Kawada to regain the IWGP Championship. He held the title for a little over three months before losing it to the bigger and stronger Scott Norton. Sasaki kept fighting for his title and came close to beating Yuji Nagata on June of 2002. He formed at this time a group called Swing-Lows consisting of younger wrestlers, Kenzo Suzuki, Hiroshi Tanahashi, Blue Wolf, and himself. After his mentor and close friend Riki Choshu left New Japan earlier in 2002, Sasaki felt no reason to stay with the company and he resigned at the close of the year. In 2003 he followed and joined Choshu's Fighting World of Japan Pro Wrestling, winning the Heavyweight Title when he beat Kenzo Suzuki on July of 2003. He would hold the title through the rest of the year, but the company would ultimately come to an end at the end of 2003. Kensuke would return to New Japan in January 2004, and was immediately labeled a heel and traitor to the company. He won the IWGP for the fourth time on March 14th, 2004, but a mere 14 days later he would lose the title against MMA fighter Bob "The Beast" Sapp. On September 1st, 2004 Sasaki, along with his very young student Katsuhiko Nakajima, won the Michinoku Pro Tohoku Tag Team Titles from Jinsei Shinzaki and Ultimo Dragon. Once back in New Japan, Sasaki defeated Kazuyuki Fujita for the IWGP Heavyweight Title on October 8th, 2004 before losing it to Tenzan two months later. After his final IWGP win he officially declared himself a freelancer and began wrestling for other promotions. He went on in All Japan Pro Wrestling to win the 2005 Champion Carnival along with winning the All Asia Tag Team Titles with Nakajima on July 26th, 2005. On July 18th, just days before winning the tag titles, he had what is considered arguably one of greatest battles/matches ever with NOAH's Kenta Kobashi. The match would last for over twenty-three minutes, and is a must to watch for any puroresu fan. On July 26th, 2007 he won the All Japan Triple Crown for the first time when he defeated Minoru Suzuki.